The present invention relates to a waveguide device and a method of forming same. More particularly, the invention is directed to a machined two-piece waveguide structure and method of manufacturing same for use in microwave network applications.
Waveguides are a well known type of electric transmission line. Waveguides serve as structural guides within which waves may be directed from a source to an end destination. Waveguides may take various formats, including straight, elbow, hybrids and transitional sections.
At the present time, the most popular means of connecting two offset ports in a waveguide system is by means of a flexible type of waveguide or by a series of elbow bends and interconnecting waveguide. The flexible waveguide is available with and without inner double ridges depending on its application. It is capped with flanges and then bent to the desired offset. Its major advantage is its flexibility, its major disadvantage however is that it requires a longer length to perform an offset when compared to the multicomponent and machined type waveguides. As well, the electrical performance of the flexible type waveguide is lesser than that of the machined or multicomponent types. Thus a flexible type waveguide may exhibit a higher voltage standing wave ratio (VSWR) as compared to a machined waveguide or multicomponent waveguide of similar configuration.
The multicomponent type waveguides, comprising a series of bends, are made by combining commercially available elbows and lengths of straight waveguide. These types of assembled bends provide good electrical performance, with a moderate VSWR, but component and assembly costs can be relatively high for large scale applications. An alternative means of waveguide manufacture where a good VSWR can be obtained is by means of extrusion. However, single quantity production of specially configured waveguide assemblies is not practical in application of this method.
In the prior art it is known to manufacture waveguides out of a series of prefabricated pieces, as disclosed in U.S. Pat. No. 2,793,989. It is also known to assemble a waveguide out of prefabricated mating pieces, where tabs, interacting with slots, are folded over to secure components of the waveguide structure together, such as disclosed in U.S. Pat. No. 2,995,806. These and other like approaches suffer from the need for an excessive number of prefabricated pieces and an excessive number of assembly steps.